Cita APA (7a ed.)

Freund, R. J., & Littell, R. C. (1991). SAS System for regression (2nd edition.). SAS Institute.

Cita Chicago Style (17a ed.)

Freund, Rudolf J., y Ramón C. Littell. SAS System for Regression. 2nd edition. Cary, NC: SAS Institute, 1991.

Cita MLA (8a ed.)

Freund, Rudolf J., y Ramón C. Littell. SAS System for Regression. 2nd edition. SAS Institute, 1991.